Intranasal administration of medicines for symptomatic relief and prevention of topical nasal conditions has been widely used. However, recently the nasal mucosa has emerged as a therapeutically viable route for drug delivery into the brain as well as systemically. Therapeutics delivered by this route include small molecules such as estradiol, sumatriptan, fentanyl, and larger molecules like calcitonin. Many factors affect intranasal drug absorption including size of the molecule, hydrophobicity, and charge. There has been a lot of effort to enhance absorption across the nasal epithelium using excipients that aid permeation. However, most absorption/permeability enhancers used over the past several decades to modify epithelial and endothelial junctional complexes and enhance paracellular permeability have suffered from poorly defined modes of action and substantial toxicity at active concentrations (Hillery, Lloyd, et al., 2001; Illum, 2012).
The cells in the nasal epithelium connect to one other through regions called tight junctions (TJ). The complexity and tissue-specific nature of TJ components and their organization has presented a further challenge to the development of effective enhancers because modes of action may vary markedly between tissue sites. Modulator substances used to increase nasal epithelial permeability to intranasally applied drugs and tracers have included calcium chelators (e.g. EGTA), bile salts, cyclodextrins, nitric oxide donors, and other chemicals (Deli, 2009). However, none of these are clinically used at present with approved/marketed nasal peptide or protein drugs (e.g. calcitonin, desmopressin, buserelin, nafarelin, and oxytocin) due to historically poor patient tolerability, associated irreversible damage to epithelial cells, or other toxicity (Hillery, Lloyd, et al., 2001; Illum, 2012). The identification and development of new modulator substances based on endogenous molecules has much potential.
Physiologic processes such as re-epithelialization (where cell migration into a damaged epithelium is facilitated by modification of TJ and extracellular matrix (ECM) components) are known to involve secreted protein modulators with high potency that act transiently and can even be “turned off” by other endogenous substances. There is a great deal of interest in discovering and developing new modulators.
We have focused on one such group of potential modulator substances, the gelatinase subclass of matrix metalloproteinases (MMPs). Matrix metalloproteinases consist of a large multigene family of well over 20 zinc-dependent endopeptidases. Although originally named for their ability to degrade extracellular matrix components, MMPs are now recognized to serve diverse roles in epithelial migration, blood-brain barrier modification in neurodegenerative diseases and stroke, and tumor progression (Bauvois, 2012; Chen and Parks, 2009; Rosenberg, 2009; Rosenberg, 2012; Rosenberg, Estrada, et al., 1998; Roy, Yang, et al., 2009). Importantly, MMPs have been identified in the normal olfactory epithelium of rodents, where they are believed to play a role in the turnover of olfactory basal cells and the development of olfactory sensory neurons (Tsukatani, Fillmore, et al., 2003).
The MMPs have commonly been divided into five distinct subclasses based on structural properties and anticipated functions (Maskos and Bode, 2003): collagenases (MMP-1, -8 and -13), gelatinases (MMP-2 and -9), matrilysins (MMP-7 and -26) and stromelysins (MMP-3 and -10). Gelatinase A and B, also referred to as MMP-2 and MMP-9, respectively, are endogenous enzymes secreted by epithelial cells under both normal and pathological conditions. MMP-9 and MMP-2 have been shown to disrupt brain endothelial cell tight junctions (TJ) by impairment of constituent proteins ZO-1, claudin-5 and occludin, resulting in increased permeability of the blood-brain barrier (Feng, Cen, et al., 2011). MMP-9 appears to enhance epithelial permeability to tracers by modifying TJ structure, e.g. transepithelial electrical conductance is increased and localization of the TJ proteins claudin-1 and occludin is altered in primary cultures of well-differentiated human airway epithelia following MMP-9 treatment (Vermeer, Denker, et al., 2009). MMP-9 may also enhance nasal epithelial permeability by partial digestion of the basal lamina, specifically by degrading type IV collagen.
Briefly, gelatinases have a number of attributes that suggest to us that gelatinases may make ideal nasal absorption/permeability enhancers: (i) gelatinases appear to facilitate epithelial repair through the promotion of a pro-migratory phenotype, characterized by a transient breakdown of the ECM and disruption of epithelial TJs, (ii) both endogenous tissue inhibitors of MMPs (TIMPs) as well as small molecule synthetic inhibitors of MMPs have been identified, potentially allowing additional control over the duration of gelatinase action, and (iii) their normal presence in the nasal epithelium, albeit at low levels and likely focused in certain areas (e.g. where resident basal cells are actively undergoing mitosis to become either mature olfactory sensory neurons/sustentacular cells in the olfactory epithelium or ciliated/goblet cells in the respiratory epithelium), may render them less toxic and better tolerated than other non-physiological modulator substances.
In general, the present invention is drawn to a method of applying gelatinases, especially Matrix Metalloproteinase-9 (MMP-9), as a modulator substance for enhancing therapeutic intranasal delivery of active compounds.